Self-inductive means for electrical oscillatory circuits.



G. VON ARGO & R. H. RENDAHL.

I 1,148,279. Patented July 27, 1915.

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W: M II. qmttozwuf UNITED STATES PATENT OFFICE.

. GEORG VON ARGO, OF BERLIN, GERMANY, AND RAGNAR HAKAN BENDAHL, OF

- LILLIENHOLM, NEAR STOCKHOLM, SWEDEN.

SELF-INDUCTIVE MEANS FOR ELECTRICAL OSCILLATORY CIRCUITS.

Specification of Letters Patent.

Patented July 27, 1915.

Original application filed January 29, 1910, Serial No. 540,914. Divided and this application filed September 30, 1913. Serial No. 792,681.

To all whom it may concern:

. Be it known that we, G'EORG VON ARco and RAGNAR HAKAN RENDAHL, subjects of the German Emperor and the King of Sweden, respectively, and residing, respectively. at Berlin, Germany, and Lillienholm, near Stockholm, Sweden, have invented certain new and useful Improvements in Self-Inductive Means for Electrical Oscillatory Circuits, of which the following is a specification.

Our invention relates to self-inductive means for electrical oscillatory circuits, particularly for transmitting arrangements in wireless telegraphy.

The particular subject matter involved in the present application is also described in our co-pending application, Serial No. 540,914, filed January 29th, 1910, from which the present application has been divided and it comprises the special arrangement of such coils relatively to each other, such that a fine variation of the self-induction is possible, even in high tension circuits. The principle arrangement of these coils is represented in Figure 5 of aforesaid application.

Our invention is illustrated in the accompanying drawing, in which Fig. 1 shows diagrammatically in elevation the arrangement of the coils according to our invention for varying the self induction within small limits, and also the connection of these coils in circuit, and Fig. 2 shows a side elevation of the middle coil 1) as an example how the coils may be wound and held in position.

Our experiments have shown that the damping of coils having the form of annular disks is a minimum when the internal diameter of the disk is approximately half the external. The height of such coils must be small relatively to this diameter. Coils of this character are particularly suitable where small variation of the self induction is required, even in transmitting arrangements in which insulation difiiculties could not be overcome heretofore.

In the accompanying drawings Fig. 1 shows diagrammatically an arrangement for stations working with three different wave lengths obtained by interpolating and cut ting out coils, a casein which it is important to be able to make small corrections of tuning of the antenn In this figure a, a and b are coils of the character illustrated in Fig. 2 and interpolated in the antennae, the two outer coils a, a being fixed and the inner coil 12 being displaceable on a rod 8 in such manner that according to the position of the central coil, in each instance relatively to the two others, the resulting self-induction is different when the direction of field produced by the coils is selected correspondingly; the fields are indicated by the respective arrows on the coils. The close proximity of b to a increases, and its close proximity to a decreases, the self-induction. The terminals e of the coils may be connected with any suitable switch for bringing about the connection to produce the resultof varying the wave length referred to hereinafter. If, for example, the station is to work with three wave lengths of 1,000, 1,500 and 2,000 meters, the conditions can be selected such that when employing all three coils (position II) a wave length of 2,000 meters is obtained which can be varied between 1800 and 2200 meters by displacing the central coil. Likewise by employing the coils b and a, position III, a wave length of 1500 meters can be obtained and by employing coils b and a, position I, a wave length of 1000 meters is obtainable, the two latter wave lengths being variable within the limits of from 1400 to 1600 meters and 900 to 1100 meters, respectively, by displacing coil 6.

The displaceable coil is preferably arranged between the two coils having fields of different direction as indicated. The case is supposed in the illustrative embodiment in which as stated above, the arrows indicate the direction of field. Coils a and b have the same direction of field so that when they approach each other the self-induction is increased, whereas coils b and a, have different directions of field so that when they are moved closer together the self-induction is decreased.

The conductor of which the coil consists is a flat ribbon Wound in a spiral and placed between two wooden frames by which the convolutions are held the desired distance apart. This is shown clearly in Fig. 2, where 0 indicates the frame and (1 indicate bolts by which the two frames are held together. We do not make, however, any claim to this particular detail frame structure as new and have merely illustrated same as a convenient form in which ribbon coils may be mounted. The middle coil 1; which as has been described before, is movable relatively 'to the two others, has a suitable opening in the center of its frame through which the rod 8 passes. The manner in which this latter coil may be moved has been omitted from the illustration since many expedients known to any one skilled in the art, may serve the purpose.

What we claim is:

1. A variable self-induction for electrical oscillatory circuits, containing at least three annular fiat disk coils adjacent to and facing each other, means permitting the varying of the connection of said coils with the oscillatory circuit for varying the self-induction by steps, and means permitting the varying of the distance between adjacent coils for gradually varying the self-induction within said steps.

2. A variable self-induction for electrical oscillatory circuits, containing at least three flat annular disk coils adjacent to and facing each other, means permitting the Varying of the connection of said coils with the oscillatory circuit for varying the self-induction by steps, and means permitting the varying of the distance between adjacent coils for gradually Varying the self-induction within the steps, the directions of fields produced by each two coils between which a. third coil is movable, being opposite to each other. v

3. A variable self-inductance for electrical oscillatory circuits, comprising two fixed coils and a movable coil disposed therebetween, each of said coils having the form of an annular disk, each of said coils adapted to be connected into said circuit and to be disconnected therefrom for varying the selfinduction by steps, and means permitting the varying of the distance between adjacent coils for gradually varying the self-induction within the steps.

GEORG VON ARGO. RAGNAR HAKAN RENDAHL.

Witnesses:

WOLDEMAR HAUPT, HARBURG O. NEIDANCE. Witnesses:

GRETA PRIM, H. CARLssoN. 

